Filament supply transformer for radio transmitters



June M L. A. GEBHARD FILAMENT SUPPLY TRANSFORMER FOR RADIO TRANSMITTERSFiled Deg. 3, 1928 INVENTOR. a fg, 1? ML A TTORNEY Patented June lei,

LOUIS A. GEIBHARD, 0F W'ASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOB, BYMESNE ASSIGN'ZEElI'Ifi TO Bill J30, INC.,

DELAWARE OF NEW YORK, N. L, A OOBPGRATIOH 0F FILAMEN'I SUPPLYTRANSFORMER FOR RADIO TRANSMITTER/S Application filed December Myinvention relates to power supply systems in general and morespecifically to power supply systems for energizing thermlomc tubes.

An object of my invention is to provide certain improvements in powersupply systems for energizing thermionic tubes.

Another object of my invention is to provide a power supply system forthermionic tubes whereby each tube receives the proper amount of energy.

Still another ob ect of my invention is to provide a power supply systemfor the energization of thermionic tubes whereby the operatlon orfailure of operation of part of the total number ply of tubes.

A general understanding of the power supply system of my invention canbe had by referring to the specification to follow and to theaccompanying drawing which is a schematic circuit diagram of the powersupply system of my invention. The circuit arrange of tubes does notafiect the supproper potential to the remainlng ment comprisescombination a master oscillator and power amplifier system employingthermionic tubes 1, 2 and 8 and associated energizing circuits, controlcircuits and a load or outnut circuit. In such circuit arrangements,thermionic tubes 1, 2 and 3 usually have different operationalcharacteristics. Thermionic tube 3 is usually of a type having a higherrated wattage output. hen such tubes are employed, the rated cathodewattage is usually much greater than that of the tubes having less poweroutput. It is often convenient to energize the respective cathodecircuits from a common source of alternating current reduced to theproper operational voltage by means of a step-down transformer. Further,it is often convenient to energize each of the cathode circuits from acommon source of alternating current and a common step-down transformer.It has her tofore been the practice to employ separate transformers forenergizing the respective cathode circuits, the primaries of which areenergized from a common source of alternating current. As an alternativearrangement, transformers have been employed de 3, 1928. Serial No.323,525.

signed to supply the proper energizing potential to the largerthermionic tube and resistances employed connected in series with thetubes of lower rating. Both of the aforepotential in the cathodecircuitsof the smaller tubes will be largely governed by thecharacteristics of the cathode circuit of the larger tube. In event theresistance of the cathode circuit of the larger tube is changed thepotential supplied to the smaller thermionic tubes will be increased.This rise in potential supplied to the smaller tubes is often sutlicientto damage the cathode of the smaller tube, if not entirely destroy it.In the power supply system of my inventionthe above mentioneddifiiculties are overcome.

' In the accompanying schematic circuit diagram, the cathode circuits ofthermionic tubes 1, 2 and 3 are en rgized by a common Source ofalternating current reduced to the proper value by transformer 4c.Transformer 4 is of the type shell constructed of suitable laminationsof thin sheets of iron or silicon steel. Transformer l is provided withamagnetic leakage path 9 which constitutes a magnetic leakage path oflow reluctance. A primary winding 5 is provided on one side of thetransformer core. Opposite the primary winding 5 a secondary winding 7is provided. On the same side and adjacent to windiu 5, a. secon darywinding 6 is provided. The self-inductance of primary winding 5 ispractically constant because of the magnetic leakage path 9 and islittle affected by the resistance of winding 7 and associated circuit.Magnetic leakage path 9 prevents exsupply wiring circuits are cessivevoltage in the associated cathode circuit of thermionic tube 3 during asudden rise of current in primary winding 5. Fluctuations in the voltageacross winding 5 are likewise prevented from materially afiectingfluctuations of voltage across winding '6. It is therefore obvious thatthe energy supplied to thermionic tubes 1 and 2 from transformer Winding6, will be of a substantially constant value. Should the cathode ofthermi" onic tube 3 burn out, excessive potentials will not be suppliedto thermionic tubes 1 and 2. Should the cathodes of thermionic tubes 1and 2 burn out, excessive potentials will not develop in the cathodecircuit of thermionic tube 3, due to the comparatively light load ofthermionic tubes 1 and 2 and magnetic leakage path 9. Any number ofthermionic tubes may be employed with the power supply sys-- tem of myinvention. The power supply system of my invention may be employed forenergizing thermionic tubes in a radio receiving set wherein a largenumber of tubes are employed or in any radio receiving system where itis desired to supply the cathode circuit with a constant potential. Itis to be understood that my invention shall notbe restricted to theforegoing specification or to the accompanying drawing but only asdefined in the appended claims.

WVhat I claim as new and desire to secure by Letters Patent of theUnited States is as follows: V

1. In a system of power distribution for thermionic tubes, thecombination of, a transformer having a primary winding connected to analternating current source and a plurality of secondary windings, saidsecondary windings being connected to a plurality of thermionic tubesand means to prevent the fluctuations of voltage across one of saidwindings from materially afiecting another of said windings.

2. In a system of power distribution for thermionic tubes, thecombination of, a transformer having a primary winding connected to analternating current source and aplurality of secondary windings, saidsecondary windings being connected to a plurality of thermionic tubesand means comprising a magnetic leakage path to maintain the inducedvoltage of said windings substantially constant.

LOUIS A. GEBHAR-D.

